Electrode substrate, thin film transistor, display device and their production

ABSTRACT

In the present invention, a lower electrode is utilized as a photomask to form a liquid-repellent region having a generally same pattern shape as that of the lower electrode and a liquid-attracting region having a generally reversed pattern shape on an insulating film. A conductive ink is coated and calcined in the liquid-attracting region to form an upper electrode having a generally reversed pattern shape to the lower electrode in a self-aligned manner, eliminating the occurrence of misregistration even when a printing method is used. Consequently, semiconductor devices such as an active matrix thin film transistor substrate can be formed using a printing method.

BACKGROUND OF THE INVENTION

The present invention relates to an electrode substrate in which a lowerelectrode and an upper electrode face each other with an insulating filmtherebetween and a semiconductor device using the same such as a thinfilm transistor and a display device, particularly to an electrodesubstrate in which a lower electrode and an upper electrode whose mainshapes are formed as reversed patterns of each other are placed in aself-aligned manner to each other and a semiconductor device such as athin film transistor and a display device using the above describedelectrode substrate, and to a method for producing them.

An electrode substrate in which a lower electrode and an upper electrodeface each other with an insulating film therebetween includes, forexample, the electrode substrate for use in a thin film transistor foran active matrix driving liquid crystal display device. In thiselectrode substrate, the lower electrode as a gate wiring/electrode, thegate insulating film, and the upper electrode as a source/drainelectrode and signal wiring are formed in this order by lamination on asubstrate comprised of glass or the like. In order to form a thin filmtransistor and a display device driven by the same on a substrate havinga large area with a high degree of accuracy, the lower electrode andupper electrode for composing wirings/electrodes each need to beprocessed to form a fine pattern and placed in an accurate alignmentwith each other. Therefore, so called photolithography method each usingseparate photomasks is used as a general method to process and form thelower and upper electrodes. In this method, a photomask that ispreliminarily processed to form a fine pattern is placed to a (positivetype) photoresist deposited on the electrode; the photoresist issubjected to photoirradiation and removed from an exposed region; theelectrode is processed by removing the electrode from the uncoveredregion of the photoresist; and finally the photoresist is removed. Theaccurate alignment of the photomask to be used for processing eachelectrode allows each electrode pattern to be accurately aligned.

A back-surface exposure method is known as a method for accuratelyaligning a lower electrode and an upper electrode. The present inventioncomprises a method for utilizing “a part” of a lower metal electrode inan auxiliary manner as a photomask for determining “a part” of thepattern shape of an upper electrode. The detail of this method isdescribed, for example, in Japanese Patent No. 3,304,671 by the sameinventor.

In recent years, a method for using a printing method that is so calleddirect-drawing method such as inkjet, plating, and offset printing hasbeen actively studied as a method for forming the electrode for use inthese electrode substrates, as described, for example, in NikkeiElectronics, No. 6.17, pp. 67–78, 2002. In these printing methods,necessary materials are placed and formed in necessary locations.Therefore, these printing methods have less number of productionprocesses and higher utilization efficiency of materials than aphotolithography process, leading to an expectation to an advantage thatan electrode substrate can be formed at a low cost. The above literatureintroduces an example in which a metal wiring having a line width of 5μm or less has been formed by an inkjet method, as an example in which afine electrode pattern has been formed by using a printing method.

A thin film transistor using the electrode substrate described above isutilized in an active matrix driving display device, and used in a flatimage-display device using, for example, liquid crystal elements,organic electroluminescent elements, electrophoresis elements and thelike as display elements. In addition, there is a move in which a thinfilm transistor using the above electrode substrate is utilized to RFID,a non-contact information medium, typified by a non-contact IC card. Ineither case, a thin film transistor is utilized in basic products thatsupport an advanced information-oriented society as a man-machineinterface device through the medium of image and communicationinformation.

In the above prior arts, if a photolithography method can be replaced bya printing method as a method for forming an electrode substrate inwhich a lower electrode and an upper electrode, which have fine patternshapes and are accurately aligned to each other, face each other with aninsulating film therebetween, production processes would be much reducedand utilization efficiency of materials would be improved, leading to anexpectation of an advantage that a large number of electrode substratescan be formed at a low cost.

However, it has been difficult to use a printing method, particularly asa method for forming electrodes in the electrode substrate with theabove construction due to the following reasons. Specifically,“misregistration” occurs when an electrode with a fine shape, which isformed using a printing method, is transferred onto a substrate from aprinting device. This causes the problem that even when at least one ofa lower electrode and an upper electrode formed thereon trough aninsulating layer can be formed in a fine pattern shape using a printingmethod, the both cannot be aligned accurately. This will be describedwith reference to FIG. 12 which shows the problem of misregistration ofelectrodes in the electrode substrate according to the presentinvention. FIG. 12( a) shows a plan view illustrating electrodes thatare well aligned and a sectional view taken along line A–A′; and FIGS.12( b) to (d) are plan views illustrating electrodes with“misregistration”. A lower electrode 2, an insulating film 3, and upperelectrodes 5 and 6 are layered in this order on a substrate 1. In FIG.12( a), both sides of the lower electrode 2 match with right end andleft end of the upper electrodes 5 and 6 respectively, that is, they arewell aligned. On the other hand, FIG. 12( b) shows an example in whichthe lower electrode 2 has shifted to the lower right on the substratesurface; FIG. 12( c) shows an example in which the upper electrodes 5and 6 have shifted to the upper left on the surface of the insulatingfilm; and FIG. 12( d) shows an example in which both misregistrationshave occurred. The occurrence of misregistration causes loss of thematching of position between the lower electrode 2 and upper electrodes5 and 6, and causes unnecessary overlapping and separation therebetween,even when electrodes are formed in fine patterns. It is known that, inthe case of an inkjet method, such “misregistration” occurs while aconductive ink ejected from a head part is flying until it attaches asubstrate, and in the case of a transfer printing method, it occurs whena pattern of a conductive ink is transferred from a transfer roll to asubstrate.

This results in a problem that when an electrode substrate of the aboveconstruction without the defect of electrode misregistration, it isnecessary to use a photolithography method in at least a part of theprocesses, which prevents the reduction of production processes andimprovement of utilization efficiency of materials. Further, there is aproblem that when a thin film transistor and a semiconductor device suchas a display device using the same are produced using the electrodesubstrate in which misregistration has occurred as a result ofproduction by a printing method, the performance and uniformity ofdevices are low and devices cannot be highly integrated with higherdefinition.

To these problems, it is an object of the present invention to providean electrode substrate and a method for producing the same in which alower electrode and an upper electrode, which have fine pattern shapesand are accurately aligned to each other, face each other inself-alignment with an insulating film therebetween, by using a printingmethod in place of a photolithography method, and to provide asemiconductor device such as a thin film transistor and a display deviceusing the above described electrode substrate and a method for producingthe same.

SUMMARY OF THE INVENTION

As means for solving the above problems, a method described below isused as a method for producing an electrode substrate comprising asubstrate, an opaque lower electrode, a light-transmitting insulatingfilm having a liquid-repellent/a liquid-attracting region on the surfacethereof and an upper electrode, wherein the lower electrode, theinsulating film and the upper electrode are layered in this order on thesubstrate, wherein a pattern shape of the lower electrode generallymatches with that of the liquid-repellent region on the surface of theinsulating film, wherein the upper electrode is mainly formed on theliquid-attracting region outside the liquid-repellent region on thesurface of the insulating film, such that the pattern shape of the upperelectrode is a self-aligned shape in which the pattern shape of thelower electrode is generally reversed. First, as a member for providingthe liquid-repellent region on the surface of the insulating film, aphotosensitive liquid-repellent film is subjected to pattern processingusing a so-called back-surface exposure method in which thephotosensitive liquid-repellent film, in which light-irradiation changesits property from a liquid-repellent property that repels liquid droppedon the surface to a liquid-attracting property that the liquid wets thesurface and spreads, is used to be subjected to the light-irradiationfrom the back-surface of the substrate using the lower electrode as aphotomask. Namely, the photosensitive liquid-repellent film is removedto form the liquid-attracting region on the surface of the insulatingfilm that is not shielded by the lower electrode, and the photosensitiveliquid-repellent film having a generally same shape as that of the lowerelectrode remains to form the liquid-repellent region on the surface ofthe insulating film that is shielded by the lower electrode. The upperelectrode, which has a pattern shape that is a generally reversed shapeof the pattern shape of the lower electrode, is formed in a self-alignedmanner by dropping a conductive ink, in which at least one of metallicultrafine particles, metal complexes, and conductive polymers isdispersed in a solvent, mainly on the liquid-attracting region of thesurface of this insulating film and subjecting it to coating andcalcining.

Further, there is formed a thin film transistor comprising an electrodesubstrate and a semiconductor film, wherein, on the electrode substrate,a gate electrode is formed as the lower electrode, and a sourceelectrode and a drain electrode are formed as the upper electrodes onthe liquid-attracting regions separated to two or more by theliquid-repellent region formed on the surface of the insulating film ina pattern shape that generally matches with the lower electrode, suchthat the pattern of the upper electrodes has a generally reversed shapeof the lower electrode, the gate electrode, and placed in a self-alignedmanner to the gate electrode; and wherein the semiconductor film isformed such that it extends over and covers at least a part of each ofthe source electrode, drain electrode and the liquid-repellent region onthe surface of the insulating film (gate electrode region) lyingtherebetween on the above electrode substrate.

Further, there is formed an active matrix thin film transistor substratecomprising an electrode substrate and thin film transistors havingsemiconductor films, wherein, on the electrode substrate, a plurality ofgate wirings/electrodes is formed as the lower electrodes, and aplurality of signal wirings, source/drain electrodes and pixelelectrodes are formed as the upper electrodes on the liquid-attractingregions separated to plural numbers by the liquid-repellent regionsformed on the surface of the insulating film in a pattern shape thatgenerally matches with the lower electrodes; wherein the semiconductorfilms are formed such that they extend over and cover at least a part ofeach of the source electrodes, drain electrodes and liquid-repellentregions (gate wiring/electrode regions) on the surface of the insulatingfilms lying therebetween on the electrode substrate; and wherein thethin film transistors are each placed at each intersection of the gatewiring and signal wiring.

Further, there is formed the active matrix thin film transistorsubstrate, wherein a plurality of gate wirings/electrodes, having ashape in which a plurality of adjacently placed ring-shaped rectangleseach having an opening is connected to each other at least at one ormore locations, are adjacently formed to each other as the lowerelectrodes; wherein signal wirings and source/drain electrodes are eachformed on the space between the rectangles in a continuous shapespreading over the connection in a self-aligned manner to the gatewirings/electrodes as the upper electrodes; and wherein the pixelelectrodes are each formed in an opening of the ring-shaped rectangle.In particular, in the shape and configuration of the plurality of gatewirings/electrodes, there is formed the active matrix thin filmtransistor substrate, wherein the width of the connection part forconnecting each of a plurality of ring-shaped rectangles each having anopening in gate wirings/electrodes and the width of the space between aplurality of gate wirings/electrodes are smaller than the width of thespace between a plurality of ring-shaped rectangles each having anopening for composing gate wirings/electrodes.

A photosensitive liquid-repellent monolayer comprising a carbon chain inwhich at least a part thereof is terminated with fluorine or hydrogen isused as a photosensitive liquid-repellent film in place of aphotoresist.

Further, as a method for producing the electrode substrate having theabove characteristics, on the surface of a light-transmitting substrateon which an opaque lower substrate, a light-transmitting insulating filmand a photosensitive liquid-repellent film are layered in this order, aphotocatalytic material, which is comprised of titanium oxide,nitrogen-doped titanium oxide, strontium titanate or the like whichshows photocatalysis with the light having the wavelengths that transmitthe substrate, insulating film and photosensitive liquid-repellent filmand does not transmit the lower electrode, is adjacently placed oradhered and is subjected to back-surface exposure; and wherein thephotosensitive liquid-repellent film is decomposed by the photocatalysisshown by the photocatalytic material that has absorbed the light thattransmitted the substrate, insulating film and photosensitiveliquid-repellent film to be processed to a pattern having a generallysame shape as that of the lower electrode. When this method is used, anopaque material to the photosensitive wavelengths of the photosensitiveliquid-repellent film may be used for at least one of the substrate orinsulating film. As a method other than this, a so-called lift-offmethod, in which the photoresist formed on the insulating film issubjected to back-surface exposure to process and form to the samepattern shape as that of the lower electrode; the photosensitiveliquid-repellent film is layered thereon; and then the photoresist isremoved, can be used to subject the photosensitive liquid-repellent filmto pattern processing to provide a generally same shape as that of thelower electrode.

The electrode substrate, thin film transistor, and active matrix thinfilm transistor substrate formed by the above configuration andproduction method are used to form a liquid crystal, electrophoresis, ororganic electroluminescent display device. Further, semiconductordevices such as an RFID tag device are formed using the above electrodesubstrate and thin film transistor to at least a part thereof.

According to the production method of the present invention, aphotosensitive liquid-repellent monolayer is used as a photosensitiveliquid-repellent film as described above in place of conventionallycommonly used photoresists. The above photosensitive liquid-repellentmonolayer is exposed using the lower electrode as a photomask to form aliquid-attracting/liquid-repellent pattern on the surface of thesubstrate. A conductive ink is coated and calcined on theliquid-attracting region of the substrate surface to form the pattern ofthe upper electrode. Since the pattern forming principle discovered bythe inventor is utilized at this time, the shape of the lower electrodewhich is a photomask for defining the general shape of the upperelectrode has the characteristics as described above.

Now, the principle of forming patterns used in the present inventionwill be described below. First, the difference as a photosensitiveliquid-repellent film between the photosensitive liquid-repellentmonolayer used in the present invention and conventional photoresistswill be described. Since photoresists generally have a lowerliquid-repellent property than the photosensitive liquid-repellentmonolayer, but can form a thick film of about 1 μm, there is provided astep height between a liquid-repellent region (photoresist part) and aliquid-attracting region to hold a conductive ink utilizing the stepheight to form an electrode pattern. On the other hand, since thephotosensitive liquid-repellent monolayer generally has a higherliquid-repellent property than photoresists, but forms a thin film ofabout 2 nm or less, it cannot utilize the step height effect likephotoresists and typically confines the conductive ink within aliquid-attracting region by the liquid-repellent action to form anelectrode pattern.

FIG. 11 shows the relation between liquid-attracting/liquid-repellentpatterns formed by a photosensitive liquid-repellent monolayer and anelectrode pattern formed by coating. The principle of forming patternsutilized in the present invention will be described using this figure.FIG. 11(1) to (3) shows the state where an electrode pattern of the sameshape is formed relative to three different liquid-repellent patterns,as plan views and sectional views taken along line A–A′ and B–B′ forrespective substrates. On a substrate 1 in each figure, a part in whicha liquid-repellent film 4 comprised of a photosensitive monolayer isformed is a liquid-repellent region, and a part in which theliquid-repellent film 4 is not formed is a liquid-attracting region.Here, a region which has a so-called contact angle, that is made betweena substrate surface and a water drop when pure water is dropped, ofabout 90° or more is defined as a liquid-repellent region, and a regionhaving a contact angle of 45° or less as a liquid-attracting region. InFIG. 11(1), the liquid-repellent region has a ring-form having a closedouter periphery surrounding a rectangular liquid-attracting regioninside. When a conductive ink is coated on this liquid-attractingregion, the conductive ink does not wet and spread over theliquid-repellent region but is confined within the liquid-attractingregion. An electrode 5 having the same shape as the above describedliquid-attracting region is obtained by calcining it. This is a generalprinciple of forming patterns that can be obtained in the same mannerwhen photoresists are used as a liquid-repellent film.

In FIG. 11(2), a part (right center part in this figure) of a ring-formliquid-repellent region in FIG. 11(1) is separated by an elongatedliquid-attracting region. In this case, when a conductive ink is coatedon the rectangular liquid-attracting region, almost all of the outerperiphery thereof being surrounded by the liquid-repellent region, theconductive ink neither wet and spread over the liquid-repellent regionin the same manner as in FIG. 11(1), nor penetrate into the separatedpart of the liquid-repellent region, which is calcined to obtain anelectrode having generally the same shape as in FIG. 11(1). It has beenfound that a necessary condition where the conductive ink does not leakfrom the separated part of the liquid-repellent region requires that thespace of the part separated by the liquid-attracting region is smallerthan the shortest space of the liquid-attracting region (short side forthe rectangle shown in this figure). This is understood to occur due toa general property of liquid that the conductive ink that is droppedtends to minimize the surface area (surface energy) as much as possible.Such an effect in which the conductive ink, a liquid material heldwithin a relatively wider liquid-attracting region, does not penetrateinto a relatively narrower liquid-attracting region which is connectedto the former region is hereinafter referred to as “non-penetratingeffect of conductive ink”.

In FIG. 11(3) on the other hand, the ring-form liquid-repellent regionin FIG. 11(1) is connected by an elongated liquid-repellent region atthe central part thereof, resulting in separation of a rectangularliquid-attracting region surrounded by the liquid-repellent region toupper and lower parts. Also in this case, when a sufficient amount ofconductive ink is coated on the rectangular liquid-attracting region,the outer periphery thereof being surrounded by the liquid-repellentregion, the conductive ink does not wet and spread over theliquid-repellent region in the same manner as in FIG. 11(1), but wetsand spreads over the above described elongated connecting part of theliquid-repellent region, combining the conductive ink coated on the twoupper and lower liquid-attracting regions into one, which is calcined toobtain an electrode having generally the same shape as in FIG. 11(1). Ithas been found that a necessary condition, where the conductive inkcoated on two liquid-attracting regions is combined into one by flowingover the liquid-repellent region separating the two regions, requiresthat the width of the elongated liquid-attracting region separating theliquid-attracting region is smaller than the shortest space of theliquid-attracting region for dropping the conductive ink (short side forthe rectangle shown in this figure). This is understood to occur due toa general property of liquid that the conductive ink that is droppedtends to minimize the surface area (surface energy) as much as possibleby taking one combined shape rather than taking two separated shapes.Such an effect in which the conductive ink, a liquid material heldwithin relatively wider liquid-attracting regions separated into two bya relatively narrower liquid-repellent region, flows over the abovedescribed narrow liquid-repellent region to be combined into one ishereinafter referred to as “crosslinking effect of conductive ink”. Thiscrosslinking effect cannot be obtained when using photoresists havingthe step height as a member for forming the liquid-repellent region, butcan only be obtained when using the photosensitive liquid-repellentmonolayer having almost no step height as in the present invention.

In the present invention, in order to form an upper electrode using aconductive ink, utilizing the above described “non-penetrating effect ofconductive ink” and “crosslinking effect of conductive ink”, the abovedescribed devices are used for the shape of a photosensitiveliquid-repellent film and the shape of a lower electrode used as thephotomask determining the shape of the photosensitive liquid-repellentfilm. The detail will be specifically described in examples below.

According to the present invention, the pattern of the upper electrodehas a shape in which the lower electrode is generally reversed by theabove effects, and so is aligned to the lower electrode in aself-alignment manner. Therefore, when a printing method such as inkjetcapable of forming fine patterns is used as a method for forming a lowerelectrode, the upper pattern formed by the printing method is also afine pattern, and is also aligned to the lower electrode in aself-alignment manner. Thus, it is possible to form an electrodesubstrate in which a lower electrode and an upper electrode, which havefine pattern shapes and are accurately aligned to each other in anself-alignment manner, face each other with an insulating filmtherebetween, without using a photolithography method, and to provide asemiconductor device such as a thin film transistor and a display deviceusing the same.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

According to the present invention, since an upper electrode having areversed pattern shape of a lower electrode is formed usingliquid-attracting/liquid-repellent regions formed by the photosensitiveliquid-repellent film to which the pattern shape of the lower electrodeis transferred utilizing the lower electrode itself as a photomask, thelower electrode and the upper electrode are aligned in a self-alignmentmanner, and the misregistration will not occur even when the lowerelectrode is formed by a printing method. Consequently, an electrodesubstrate in which a lower electrode and an upper electrode areaccurately aligned through an insulating film can be formed by aprinting method. Wirings/electrodes placed in self-alignment crossingeach other through an insulating film can be printed by devising thepattern shape of a lower electrode so that the non-penetration effectand the crosslinking effect of conductive ink can be utilized whencoating and forming an upper electrode using the conductive ink. Theeffect of reducing the number of processes for producing an electrodesubstrate by a printing method is shown in FIG. 16. A conventionalphotolithography method requires eight processes for forming oneelectrode, that is, 19 processes in total. On the other hand, the use ofthe printing method of the present invention allows the production byseven processes, less than the half of the conventional method, theeffect of improving productivity being obvious.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view and a sectional view illustrating one example ofan electrode substrate and a thin film transistor of the presentinvention, and their production;

FIG. 2 is a plan view of a thin film transistor of the present inventionprepared by a printing method;

FIG. 3 shows-plan views and sectional views illustrating a 2×2 activematrix thin film transistor substrate of the present invention, andtheir production;

FIG. 4 is a plan view illustrating the relation of the shapes between alower electrode and a signal wiring/drain electrode of the presentinvention;

FIG. 5 shows a plan view illustrating the shape of a lower electrode(gate wiring/electrode) of the present invention;

FIG. 6 is a plan view illustrating an m×n active matrix thin filmtransistor of the present invention and its production;

FIG. 7 is a plan view illustrating an m×n active matrix thin filmtransistor of the present invention and its production;

FIG. 8 is a plan view illustrating an m×n active matrix thin filmtransistor of the present invention and its production;

FIG. 9 is a plan view illustrating an m×n active matrix thin filmtransistor of the present invention and its production;

FIG. 10 is a sectional view illustrating an m×n active matrix thin filmtransistor of the present invention and its production;

FIG. 11 is a view illustrating the principle of forming coated electrodepatterns by a photosensitive liquid-repellent monolayer utilized in thepresent invention;

FIG. 12 is s plan view and s sectional view illustrating the problem ofmisregistration of electrodes in an electrode substrate;

FIG. 13 is a view illustrating a back-surface exposure patterning methodof a photosensitive liquid-repellent film of the present invention;

Fog. 14 is a plan view and a sectional view illustrating main deviceconfiguration of a display device of the present invention;

FIG. 15 is a view illustrating a back-surface exposure method of aphotosensitive liquid-repellent film and device configuration of thepresent invention; and

FIGS. 16A and 16B are views illustrating the effect of reducing thenumber of processes for producing an electrode substrate of the presentinvention.

The meaning of reference numerals is as follows:

1 . . . substrate, 2 . . . lower electrode, gate wiring/electrode, 3 . .. insulating film, 4 . . . photosensitive liquid-repellent film, 5 . . .upper electrode, signal wiring/drain electrode, 6 . . . upper electrode,pixel electrode/source electrode, 7 . . . semiconductor film, 8 . . .ring-shaped rectangle having opening of gate wiring electrode, 9 . . .connection part of gate wiring, 10 . . . space between adjacent gatewirings/electrodes, 11 . . . gate terminal, 12 . . . lower electrode forforming signal terminal, 13 . . . signal terminal, 14 . . . protectivefilm, 15 . . . through hole, 16 . . . active matrix thin film transistorsubstrate, 17 . . . gate scanning circuit, 18 . . . signal circuit, 19 .. . control circuit, 20 . . . display element, 21 . . . opposingelectrode, 22 . . . heating mechanism, 23 . . . supporting plate, 24 . .. photocatalyst, 25 . . . hole.

PREFERRED EMBODIMENTS OF THE INVENTION

Hereinafter, several examples of the present invention will bespecifically described with reference to drawings. First, a lightpatterning method by back-surface exposure of a photosensitiveliquid-repellent film, which is a common technology, will be describedwith reference to FIG. 13.

First, there is provided an electrode substrate in which a lowerelectrode 2, a light-transmitting insulating film 3 and a photosensitiveliquid-repellent film 4 are layered in this order on alight-transmitting substrate 1. For example, a quartz substrate having athickness of 1 mm is used as the substrate 1; a Cr thin film having athickness of 140 nm is used as the lower electrode 2; a silicon oxidefilm having a thickness of 400 nm is used as the insulating film 3; anda fluorinated alkyl-based silane coupling agent typified by CF₃(CF₂)₇(CH)₂SiCl₃ and the like, which is a liquid-repellent monomer having acarbon chain terminated with a fluorine group in at least a part thereofis used as the photosensitive liquid-repellent film 4, and these areformed in the following methods respectively. The lower electrode 2 wasformed by depositing a Cr thin film having a thickness of 400 nm at asubstrate temperature of 200° C. using a DC magnetron sputtering deviceand then processing it by using a ceric ammonium nitrate solution as anetching solution in a photolithography method (FIG. 13( a)). Theinsulating film 3 was deposited at a substrate temperature of 350° C.using a plasma chemical vapor deposition method (plasma CVD method),using tetraethoxysilane (TEOS) and oxygen (O₂) as source gases. Thephotosensitive liquid-repellent film 4 was formed by thoroughly cleaningthe surface of the substrate 1 on which the lower electrode 2 and theinsulating film 3 are layered in this order, then coating a solutionprepared by dispersing the above silane coupling agent in afluorine-based solvent by spin coating, dip coating, spraying or thelike and drying it (FIG. 13( b)). The above substrate was subjected toso-called back-surface exposure by irradiating the back surface with thelight emitted by a low pressure mercury lamp for about 30 minutes (FIG.13( c)). The light path of radiation is indicated by arrows in thefigure. After the completion of the back-surface exposure, thephotosensitive liquid-repellent film 4 is removed from thelight-irradiated region (non-shielding region by the lower electrode) onthe surface of the insulating film 3 to form a liquid-attracting region,and the photosensitive liquid-repellent film remains on thenon-irradiated region (shielding region by the lower electrode) on thesurface of the insulating film 3 to form a liquid-repellent region. Thiswas confirmed by the following methods. The presence or absence of thephotosensitive liquid-repellent film was determined by determining thepresence or absence of a fluorine element using photoelectronspectroscopy such as XPS and UPS, and TOF-SIMS (Time-of-Flight SecondaryIon Mass Spectrometry). In addition, a contact angle was measured bydropping pure water on the surface of the insulating film 3. Thenon-irradiated region showed a contact angle of 100° to 120°, while thelight-irradiated region showed 30° or less. In addition, when thesubstrate was immersed in pure water and pulled up, the pure wateradhered only to the light-irradiated region (non-shielding region by thelower electrode) on the surface of the insulating film 3, and theoverlapping width at the edges of the pure water and the lower electrode2 as observed in the vertical direction to the substrate was 1 μm orless.

From the above results, it was ascertained that the photosensitiveliquid-repellent film 4 is processed to a generally same pattern shapeas that of the lower electrode 2 by the back-surface exposure methodutilizing the lower electrode 2 as a photomask (FIG. 13( d)).

In the following examples, the shape of the lower electrode 2 that isused as a photomask is devised depending on purposes so that thephotosensitive liquid-repellent film is processed to a generally samepattern shape as that of the lower electrode 2. At this time, the shapeof the lower electrode 2 and that of the photosensitive liquid-repellentfilm 4 are overlapped in a plan view of an electrode substrate, and sothey cannot be distinguishably expressed. In the following figures, thedescription of 2 and 4 in a figure means that the photosensitiveliquid-repellent film 4 is disposed on the lower electrode 2 in agenerally same shape. The substrate 1 and the insulating film 3 are alsodescribed by 1 and 3 in a plan view as the same meaning.

EXAMPLE 1

FIG. 1 shows a plan view and a sectional view illustrating one exampleof an electrode substrate and a thin film transistor of the presentinvention and their production. The lower electrode 2 and the insulatingfilm 3 are layered in this order on the substrate 1, for example, usingthe same members and forming method as those in FIG. 13. However, in thepresent example, the pattern shape of a gate electrode which is thelower electrode 2 has two openings placed adjacent to each other. Inaddition, in the present invention, as the photosensitiveliquid-repellent film 4 is coated by a dip coating method, thephotosensitive liquid-repellent film 4 adheres to the back surface ofthe substrate 1 other than the insulating film 3 (FIG. 1( a)). Byback-surface exposure, the photosensitive liquid-repellent film 4 isremoved from the back surface of the substrate 1, and forms aliquid-repellent region having a generally same pattern shape as that ofthe lower electrode 2 on the surface of the insulating film 4 (FIG. 1(b) to (c)). A conductive ink, which is composed of a liquid materialcontaining at least one of metallic ultrafine particles, metal complexesand conductive polymers, is coated on two liquid-attracting regionssurrounded by the liquid-repellent region formed on the insulating film3 and calcined to form upper electrodes 5 and 6 (FIG. 1( d)). Theconductive ink that may be used includes a liquid material havingproperties that it is repelled from the liquid-repellent region formedby the photosensitive liquid-repelled film 4 and it wets and spreadsover the liquid-attracting region from which the photosensitiveliquid-repellent film 4 is removed, and showing a sufficiently lowresistance value after the calcining. A specific material that can beused includes a solution in which metallic ultrafine particles or metalcomplexes mainly composed of Au, Ag, Pd, Pt, Cu, Ni or the like andhaving a diameter of about 10 nm or less are dispersed in a solvent suchas water, toluene or xylene. Further, for forming ITO (indium tin oxide)of a transparent electrode material, a solution in which metal alkoxidessuch as In(O-i-C₃H₇)₃ and Sn(O-i-C₃H₇)₃ are dispersed in a water,alcohol solvent. Furthermore, an aqueous solution of PEDOT(poly-3,4-ethylenedioxythiophene), polyaniline (PAn), polypyrrole (PPy)or the like doped with PSS (polystyrene sulfonic acid), a conductivepolymer such as, can also be used as the transparent electrode materialother than this. It was possible to form the upper electrodes 5 and 6having a film thickness of about 100 nm using any of the above materialsby dropping them in an amount enough to cover the above twoliquid-attracting regions and then calcining them at an appropriatetemperature of about 80 to 500° C. in vacuum or in air. In the presentexample, the upper electrodes 5 and 6 were formed as two rectangularshapes on the liquid-attracting regions other than the liquid-repellentregion on the surface of the insulating film, and the pattern shape wasa self-aligned shape in which the pattern shape of the lower electrode 2was generally reversed.

Cr was used as the lower electrode material in the above example, butany suitable opaque material to the exposure wavelengths may be used.For example, Al, Mo, Au, Ag, Pd, Cu, and the like may be used. Further,quartz, silicon oxide and a fluorinated alkyl-based silane couplingagent were used for the substrate 1, the insulating film 3 and thephotosensitive liquid-repellent film 4, respectively, but any suitablematerial other than these may be used. However, the materials for thesubstrate 1 and the insulating film 3 are limited depending on thematerial for the photosensitive liquid-repellent film 4, because theyneed to transmit the exposure wavelengths of the photosensitiveliquid-repellent film 4. A fluorinated alkyl-based silane coupling agentwas used as the material for the photosensitive liquid-repellent film,but other materials may be used, provided they are liquid-repellentmonomers having a carbon chain terminated with a fluorine group in atleast a part thereof. For example, perfluorooxetane derivatives, such asperfluorooxetane having a fluorine substituent in a side chain asdescribed in JP-A-2001-278874, may be used. However, as these materialsfor the photosensitive liquid-repellent film have an exposure wavelengthof 300 nm or less, the materials for the substrate 1 and the insulatingfilm 3 require those materials that transmit the wavelengths of 300 nmor less (having a band gap of 4 electron volts (eV) or higher), andquartz and silicon oxide were used, respectively, in the above example.The silicon film may be a film prepared by coating and calcining in asol-gel method, other than forming it by plasma chemical vapordeposition. Further, silicon nitride (Si₃N₄), silicon oxynitride (SiON),aluminum oxide (Al₂O₃) or zirconium oxide (ZrO₂) may be used other thansilicon oxide. Further, the material for the substrate 1 may besynthetic quartz.

A method for shifting the photosensitive wavelengths of thephotosensitive liquid-repellent film to a long wavelength of 300 nm orhigher includes the following two ways. One is a photosensitiveliquid-repelling film comprised of a molecule having a dye skeleton thatthermally decomposes by absorbing the light having a wavelength of 300nm to 700 nm, which specifically includes compounds 1 and 2 below.

Methods for synthesizing these compounds are shown below.

(Synthesis of Compound 1)

The compound 1 is synthesized by reactions (i) to (iii) below.

(i) Reduction of Liquid-repellent Material

Krytox 157FS-L made by Du Pont (average molecular weight 2,500) (50parts by weight) is dissolved in PF-5080 made by 3M (100 parts byweight). The solution is added with lithium aluminum hydride (2 parts byweight) and heated and stirred for 48 hours at 80° C. The reactionsolution is poured into ice water, and the lower layer is dispensed,washed with 1% hydrochloric acid and then washed with water until thewashed solution becomes neutral. After removing water in the solutionafter washing by filtering with a filter paper, PF-5080 is evaporated byan evaporator to obtain a compound 3 (45 parts by weight) in which theterminal of Krytox 157FS-L is transformed to CH₂OH.F—[CF(CF₃)—CF₂O]_(n)—CF(CF₃)—CH₂OH  n≅4

Compound 3

(ii) Introduction of Dye Skeleton

The compound 3 (45 parts by weight) is dissolved in HFE-7200 made by 3M(100 parts by weight). The solution is added with Reactive Yellow 3(another name: Procyon Yellow HA) (12 parts by weight), ethanol (100parts by weight) and sodium carbonate (2 parts by weight) and refluxedfor 30 hours. The structure of Reactive Yellow 3 is shown below.

The solvents in the reaction solution (HFE-7200 and ethanol) areevaporated by an evaporator. The residue is added with a mixture ofHFE-7200 (100 parts by weight), hydrochloric acid of 35% by weight (100parts by weight) and ice water (100 parts by weight), vigorously stirredand then left at rest. The lower layer is dispensed and washed withwater until the washed solution becomes neutral. After removing water inthe solution after washing by filtering with a filter paper, HFE-7200 isevaporated by an evaporator to obtain a compound 4 (45 parts by weight)in which Reactive Yellow 3 is combined with the compound 3.

(iii) Reaction for Introducing Binding Site

The compound 4 (45 parts by weight) is dissolved in HFE-7200 (100 partsby weight). When the resultant solution is cooled to around 0° C., it isadded with Sila-Ace S330 made by Chisso Corporation (10 parts byweight), N,N-dicyclohexylcarbodiimide (10 parts by weight),dichloromethane (20 parts by weight) and stirred for 3 hours. Thereaction solution is returned to room temperature and further stirredfor 30 hours. The reaction solution is left at rest and the lower layeris dispensed when the reaction solution is separated into two layers.Note that a hazy layer, which will be produced between the upper andlower layers, must not be added to the lower layer. The lower layer iswashed with dichloromethane (20 parts by weight) several times and thenfiltered with a filter paper. Then, the solvent (HFE-7200) in thesolution was evaporated by an evaporator to obtain the target compound 1(40 parts by weight).

(Synthesis of Compound 2)

The compound 2 (40 parts by weight) was obtained in the same manner asthe synthesis of the compound 1, except that Mikacion Brilliant Blue RS(7 parts by weight) was used in place of Reactive Yellow 3 (12 parts byweight).

The chemical structure of Mikacion Brilliant Blue RS is shown below.

In some cases, a sodium sulfonate part is in the form of sulfonic acid.In these cases, it is transformed to sodium sulfonate with sodiumhydroxide or the like before use.

When the above compounds 1 and 2 are used as the photosensitiveliquid-repellent film, the substrate 1 and the insulating film 3 mayonly transmit any wavelengths within the above wide wavelength range.Therefore, a thin film having a thickness of 300 nm comprised oftantalum oxide (Ta₂O₅), zirconium oxide (ZrO₂) or lanthanum oxide(La₂O₃), as another inorganic material than silicon oxide (SiO₂), whichis formed by plasma chemical vapor deposition or a sol-gel method, maybe used for the insulating film 3. Further, a spin-coated film ofpolyvinylphenol (PVP) or polymethylmethacrylate (PMMA) may be used as anorganic material. A typical glass substrate such as Corning 1737 orvarious plastic substrates may be used for the substrate 1.

Another method for shifting the photosensitive wavelengths of thephotosensitive liquid-repelling film 4 to longer wavelengths uses aphotocatalytic material in at least a part of the insulating film 3. Thephotocatalytic material has the effect of absorbing light to produceholes and electrons having strong oxidizing and reducing power in thefilm, decomposing organic materials adjacent to the photocatalyticmaterial.

In this case, the above described all materials can be used for thephotosensitive liquid-repellent film 4. For example, a photocatalyticmaterial comprised of, for example, titanium oxide (TiO₂) is coated by asol-gel method to form a film having a thickness of about 10 nm betweenthe insulating film 3 and the photosensitive liquid-repellent film 4 asdescribed by Tadanaga and Minami in Material Integration, 14(10), pp.9–13 (2001). Since titanium oxide absorbs the light having a wavelengthof 400 nm or less to cause photocatalysis, materials transmitting thelight having a wavelength of 400 nm or less can be used for thesubstrate 1 and the insulating film 3. In this case, glass substratesand plastic substrates comprised of polyimides with high lighttransmittance may be used for the substrate 1. Furthermore, the abovedescribed inorganic materials can be used for the insulating film 3.However, organic materials had better not be used because they aredecomposed by the photocatalytic material.

This is the same for a semiconductor material 7 to be describedhereinafter, and so organic materials had better not be used for thesame. Further, when using a so-called visible-light-responsivephotocatalytic material which absorbs visible light of 600 nm or less tocause photocatalysis, materials that transmit the light having awavelength of 600 nm or less can be used for the substrate 1 and theinsulating film 3. Therefore, all the above described inorganicmaterials can be used.

A method for processing the photosensitive liquid-repellent film 4 usinga photocatalytic material other than the above, in which organicmaterials can be used for the insulating film 3 and the semiconductormaterial 7, will be described in (Example 6).

A thin film transistor can be composed by forming the semiconductor film7 on the electrode substrate of the present invention formed asdescribed above, such that the semiconductor film 7 extends over andcovers at least a part of each of the source electrode 5, drainelectrode 6 and the insulating film surface having the gate electrode 2in the lower part thereof. Following materials and production methodscan be used for the semiconductor film 7. As for inorganic materials, anamorphous silicon film having a thickness of about 200 nm is formed byplasma chemical vapor deposition at a substrate temperature of 250° C.using silane and hydrogen (SiH₄+H₂). Then, the amorphous silicon film isprocessed to an island shape by dry etching using SF₆ as an etching gasto obtain the semiconductor film 7. Further, it may also be subjected tolaser annealing to provide a polycrystalline silicon film. Wheninorganic materials are thus used for the semiconductor film 7, it isdesirable to use inorganic materials such as silicon oxide and siliconnitride also for the insulating film 3. Further, the removal of thephotosensitive liquid-repellent film from the surface of the insulatingfilm 3 before forming the semiconductor film 7 is preferable forstabilizing the interface between the insulating film 3 and thesemiconductor film 7, thus capable of obtaining good transistorcharacteristics. For example, the use of amorphous silicon providedequal performance to typical thin film transistors, in whichfield-effect mobility is 0.5 cm²/Vs; threshold voltage is 2 V; andon/off current ratio is seven digits. As for organic materials, in thecase of low-molecular weight substances, acene-based materials typifiedby pentacene and thiophene oligomers are used for film formation byvacuum deposition at a substrate temperature from room temperature to100° C. Mask deposition or photolithography using oxygen as the etchinggas is used to form the semiconductor film 7 processed in island shape.In the case of pentacene, it can be modified to a solubleprecursor/derivative material in a solvent such as toluene or chloroformfor film forming by a coating method such as casting, spin coating ordip coating. Furthermore, in the case of polymers, polythiophenes suchas poly-3-hexylthiophene (P3HT) having a regio-regular structure (havingthe orientation in which the whole chain aligns in the same directionwith head and tail adjacent to each other) that is a highly regularnano-structure, polyfluorenes such as a copolymer offluorene-bithiophene (F8T2), and polyphenylenevinylene (PPV) are usedfor film forming by the coating methods described above. In the case ofusing organic materials for the semiconductor film 7, the transistorcharacteristics are improved when the semiconductor film 7 is formed onthe photosensitive liquid-repellent film 4 on the gate electrode 2without removing the photosensitive liquid-repellent film 4. Forexample, the deposited film of pentacene formed on the photosensitiveliquid-repellent film 4 showed the performance of a field effectmobility of 1.0 cm²/Vs, a threshold voltage of −2 V, and an on/offcurrent ration of seven digits. However, when the pentacene film wasformed on the insulating film from which the photosensitiveliquid-repellent film 4 had been removed, the performance degraded to afield effect mobility of 0.2 cm²/Vs, a threshold voltage of −5 V, and anon/off current ration of four digits. It is contemplated that thephotosensitive liquid-repellent film 4 has the effect in improving theorientation order of organic semiconductor materials.

EXAMPLE 2

In this example, the case in which the lower electrode 2 is formed by aprinting method such as ink jet and the semiconductor film 7 is formedby casting will be described with reference to FIG. 2 showing a planview of a thin film transistor. The same material and printing method asthose used for the upper electrodes 5 and 6 in Example 1 can be used forthe lower electrode 2. Other than the lower electrode 2, the samematerials and methods as those used in Example 1 can be used. When anink jet method is used, the lower electrode 2 which forms the gateelectrode exhibits a shape in which dots are overlapped each other asshown in the figure. This is due to the fact that the conductive inkejected from the head of ink jet isotropically wets and is spread overthe uniform substrate 1 leaving the trace of a dot shape during theejection. Even when the shape of the lower electrode 2 is thus deformeddepending on the forming method, the photosensitive liquid-repellentfilm pattern having a generally same pattern as the shape of the lowerelectrode 2 is formed on the insulating film 3. Therefore, the upperelectrodes 5 and 6 can be formed on the insulating film 3 as a shape inwhich the shape of the lower electrode 2 is generally reversed. When forexample P3HT is coated on the upper electrodes 5 and 6 by casting, thesemiconductor 7 may be formed in a misaligned position (an exampleshifted in an upper-right direction is shown in the figure). Even whensuch misregistration is produced, the thin film transistor of thepresent invention provided uniform switching characteristics. This isdue to the following reason. Generally, the thin film characteristicsvary and become nonuniform depending on the variations of the parasiticcapacitance formed by the member sandwiched by the lower electrode 2,gate electrode, and the upper electrodes 5 and 6, source/drainelectrodes. In a general thin film transistor structure, a so-calledtop-contact structure is used, in which the upper electrodes 5 and 6 areformed on the semiconductor film 7. In this case, when the upperelectrodes and the semiconductor film are positioned in misregistration,the parasitic capacitance varies and the characteristics becomenonuniform. On the other hand, in the present invention, the upper andlower electrodes are formed in a self-alignment manner to preventmisregistration. Further, the present invention provides a so-calledbottom-contact structure in which the upper and lower electrodes areformed first and then the semiconductor film 7 is formed thereon, so thesemiconductor film 7 is not sandwiched by the upper and lower electrodesand does not contribute to the parasitic capacitance. Consequently, thethin film transistor of the present invention provides uniform thin filmtransistor characteristics even when the upper and lower electrodes 2and 4 and semiconductor film 7 are formed by a printing method. If theinsulating film is also formed by a printing method, all can be formedby a printing method, thereby providing a thin film transistor havinguniform characteristics.

EXAMPLE 3

In the present example, a 2 row×2 column active matrix thin filmtransistor substrate comprising four thin film transistors formed at theintersections of two gate electrode wirings which form at least a partof the lower electrodes and two signal wirings which form at least apart of the upper electrodes, and a method for producing the same aredescribed with reference to FIG. 3 showing a plan view and a sectionalview. Materials and forming methods for respective layers of the presentexample are the same as those in Examples 1 and 2, so they will not bedescribed except specifically required.

In the present example, in order to utilize the above described“non-penetrating effect of conductive ink” and “crosslinking effect ofconductive ink” to form signal wirings/drain and source electrodes/pixelelectrodes, the shape having the features shown in FIG. 3( a) is used asthe pattern shape of the lower electrode 2 for mainly composing gatewirings/electrodes. Specifically, two gate wirings/electrodes, each ofwhich is characterized by a shape in which adjacently placed tworing-shaped rectangles 8 each having an opening are connected at oneconnection part 9, are adjacently placed to each other through a space10. A rectangular gate terminal 11 is connected at the left edge of thegate wirings/electrodes 2. Lower electrodes 12 for forming terminals tobe utilized for forming terminals of signal wirings/drain electrodes 5are adjacently placed at the upper and lower portions of the two gatewirings/electrodes through the spaces 10. Particularly, when a shape ofthe lower electrode 2, in which the width of the connection part 9 ofthe gate wiring/electrode (a in FIG. 3( a)) and the width of the space10 between the gate wirings/electrodes and between the gatewiring/electrode and the lower electrode 12 for forming a terminal (b inFIG. 3( a)) are smaller than the width of the space between the adjacentrectangles 8 each having a ring-shaped opening (c in FIG. 3( a)), isused to coat and calcine a conductive ink along the space between therectangles, an upper electrode 5, which acts as a signal wiring and adrain electrode, was formed. The upper electrode 5 had a continuouslinear shape in which the connection part 9 was bridged along the spacebetween the above described rectangles 8. Further, when a conductive inkwas coated and calcined in the opening, the liquid-attracting region, ofthe ring-shaped rectangle 8, the upper electrode 6, which acts as thesource electrode and pixel electrode, was formed in the opening in aself-alignment manner (FIG. 3( b)). The semiconductor films were formedon above described electrode substrate, such that the semiconductorfilms extend over and cover at least a part of each of the signalwirings/source electrodes 5, drain electrodes/pixel electrodes 6 and theinsulating film surface having the gate wirings/electrodes 2 in thelower part thereof on the electrode substrate. Thereby, the activematrix thin film transistor substrate is completed in which four thinfilm transistors are placed on respective intersections of the gatewirings/electrodes 2 and signal wirings/drain electrodes 5. The point ofthe present example is to set the width of the space between therectangles 8, that is, the width of the upper electrode c wider than thewidth a of the space 10 and the width b of the connection part 9 so thatwhen coating and forming the upper electrode 5, which is the signalwiring/drain electrode, using the conductive ink, the conductive inkdoes not penetrate into the space 10 between the gate wirings/electrodes2 to cause the short circuit between the upper electrodes 5, and theconductive ink does not stop spreading over the connection part 9 tobreak the upper electrode 5, thereby forming the upper electrode 5continuously in the longitudinal direction, utilizing the“non-penetrating effect of conductive ink” and “crosslinking effect ofconductive ink”. Specifically, the above effect was produced by settinga=b=3 μm relative to c=15 μm.

The plan view illustrating the relation between the shape of the lowerelectrode and the shape of the signal wiring/drain electrode is shown inFIG. 4. FIG. 4( a) shows the case in which the width b of the space 10is nearly equal to or more than the width c of the upper electrode 5. Inthis case, the conductive ink penetrated into the space 10 to cause theshort circuit between the adjacent upper electrodes 5. FIG. 4( b) showsthe case in which the width a of the connection part 9 is nearly equalto or more than the width c of the upper electrode 5. In this case, theconductive ink did not spread over the liquid-repellent region on theconnection part 9 to cause disconnection. If the width a of theconnection part 9 can be set large as in FIG. 4( b), the resistance ofthe gate wiring/electrode can be reduced, which would be advantageous tothe thin film transistor substrate for use in the display device. As ameasure to the disconnection, FIG. 4( c-1) shows an example in which theconductive ink is re-coated on the connection part for connection. Atthis time, it will be desirable to remove the photosensitiveliquid-repellent film with a HeCd laser or the like before there-coating and to use a conductive ink having a relatively higherviscosity. However, the problem of the correction by this method is thatit requires time.

FIG. 4( c-2) shows an example in which the shape of the lower electrodeis devised so as to prevent disconnection failure. In this example, aplurality of connection parts 9 is provided (3 parts in the figure),wherein even when the total width of the connection parts 9 is equal toor more than the width c of the upper electrode, each width of theconnection parts is less than the width c of the upper electrode.Thereby, the each connection part can be passed over by the“crosslinking effect of conductive ink” to prevent the disconnection ofthe upper electrode 5 and at the same time the gate wiring/electrode canreduce the resistance. Specifically, disconnection occurred whenproviding one connection part having b=15 μm relative to c=15 μm, butwhen the connection part is divided into three each having the width of5 μm, the disconnection was eliminated by crosslinking.

Further, FIG. 4( c-3) shows an example in which the ring-shapedrectangle is curved inside at the connection part 9 to locally increasethe width c of the upper electrode. In this example, the width c can bedesigned wider than the width a of the connection part 9, so that the“crosslinking effect of conductive ink” is enhanced and the signalwiring part of the upper electrode can be formed without disconnection.

In the examples shown in FIGS. 3 and 4, in the gate wirings/electrodes2, adjacently placed ring-shaped rectangles 8 each having an opening areplaced such that the upper and lower edges thereof are alignedhorizontally. However, the present invention needs not be limited tothis. For example, as shown in FIG. 5, a configuration, in which therectangles 8 are placed in the positions alternately shifted up anddown, may be adopted. In this case, the space 10 between the gatewirings/electrodes are not crossed linearly with the space between therectangles 8 in which the signal wirings are to be formed. It wasconfirmed that this configuration has the effect to prevent the failurethat when a conductive ink is dropped on the space between therectangles 8, the ink does not flow into the space 10 in both right andleft directions to cause disconnection or short circuit. Thus, it ispossible to suppress the failure of disconnection and short circuit ofthe signal wirings formed in a coating process, not only by utilizingthe non-penetrating effect of conductive ink by reducing the width ofthe space 10 as described above but also by devising the shape of thegate wirings/electrodes.

As described hereinabove, it was possible to form an active matrix thinfilm transistor substrate by forming an electrode substrate in which agate wiring/electrode faces a signal wiring/drain electrode and a sourceelectrode/pixel electrode through an insulating film in a self-alignedmanner and placing a thin film transistor at the intersection of thegate wiring/signal wiring. All of the active matrix thin film transistorsubstrate can be produced by a printing method using the methods shownin Examples 1 and 2.

Finally, the conductive ink material for forming the upper electrodes 5and 6 is referred to. When this substrate is used for thelight-transmitting display device, the pixel electrode/source electrode6 needs to be transparent, so coating-type ITO materials and conductivepolymers described in Example 1 are used. When it is used for areflective display device, it is effective to use Ag or the like havinga high degree of reflection in the visible light wavelength region forimproving the display performance.

EXAMPLE 4

In the present invention, a m row×n column active matrix thin filmtransistor substrate comprising m×n pieces of thin film transistorsformed at the intersections of m pieces of gate electrode wirings whichform at least a part of the lower electrodes and n pieces of signalwirings which form at least a part of the upper electrodes, and a methodfor producing the same are described with reference to FIG. 6 showing aplan view and FIG. 10 showing a sectional view. Basic configuration isthe same as that in Example 3. First, m pieces of gatewirings/electrodes 2, in which adjacently placed n pieces of ring-shapedrectangles each having an opening are connected to each other at leastat one connection part 9 or more (two in the present example), areadjacently placed to each other through spaces 10 (FIG. 6).Particularly, when the width b of the space 10 and the width a of eachof the connection parts 9 are designed to be equal to or more than thespace c between the rectangles each having a ring-shaped opening, it ispossible to form n pieces of upper electrodes 5 which act as the signalwirings/drain electrodes in a continuous linear shape self-aligned tothe lower electrode by spreading over the liquid-repellent regions onthe connection parts 9, by coating a conductive ink on the space c andcalcining it. The penetration of the conductive ink into the spaces 10to short the upper electrodes 5 to each other will not occur.

Further, in the present example, an integrally formed lower electrode 12for forming terminals is placed surrounding the outer periphery of mpieces of the gate wirings/electrodes 2 as a part of the lower electrode2. In order to prevent the formation of the upper electrodes 5 at theedge of the substrate 1 outside of the lower electrode 12 for formingterminals, a sealing mask may be applied on this part and removed afterforming the upper electrodes 5. Furthermore, in the present invention,the width of the signal terminal part 13 for the lower electrode 12 forforming terminals was designed to be wider than the width c of the upperelectrode. This is not only just for reducing the contact resistancewith the signal circuit to be described hereinafter by increasing thearea of the upper electrode terminal, but also for utilizing it as inkreservoirs for coating and forming the relatively long signal wirings 5with a conductive ink. Namely, when the conductive ink dropped along thespace having the width c for forming the wirings 5 is too much, theconductive ink flows into the signal terminal part 13, and when it istoo few, the conductive ink is supplied from the signal terminal part13. Thus, the ink reservoirs act such that the upper electrodes 5 can beformed with suitable amount of conductive ink (FIG. 7). By forming thesemiconductor 7 on this electrode substrate using the similar placement,similar method and similar material as in Example 3, m×n pieces of thinfilm transistors are formed at the intersections of m pieces of gatewirings 2 and n pieces of signal wirings 5 (FIG. 8). Further thereon, aprotective film 14 is formed. After forming the protective film 14,through holes 15 are formed by removing the protective film from abovethe pixel/source electrode 6, gate terminal 11, and signal terminal 13.The protective film and the thorough holes are formed, for example, byforming silicon nitride or silicon oxynitride using plasma chemicalvapor deposition at a substrate temperature of 150° C. or higher, and bysubjecting it to dry-etching processing by photolithography using SF₆ asan etching gas. At this time, it will be no problem that the position ofthe through holes is a little shifted, so printing of photoresist may beused for forming the same. Further, the protective film and throughholes can be formed in one operation by mask exposure and developmentafter coating and temporary calcining of an organic film comprised of aphotosensitive polyimide or the like. When the printing method describedin Example 3 and the above method for forming protective film/throughholes are used in combination, an active matrix thin film transistorsubstrate can be formed in which the gate wiring/electrode 2 and thesignal wirings/pixel electrodes 5 and 6 are placed in self-alignmentthrough the insulating film 3 by using only a printing method withoutusing photolithography. Furthermore, it is needless to say that when thelower electrode 2 is finely processed and formed using photolithography,the lower electrodes 5 and 6 can also be finely formed as a reversedpattern shape thereof, thereby forming an active matrix thin filmtransistor substrate with high definition.

EXAMPLE 5

In the present example, the display device using the active matrix thinfilm transistor substrate of the present invention will be describedwith reference to FIG. 14 showing a plan view and a sectional view ofthe main device configuration. A gate scanning circuit 17 is connectedto a gate terminal 11 of an active matrix thin film transistor substrate16, and a signal circuit 18 is connected to a signal terminal 13thereof, by a TAB (Tape Automated Bonding) method or a COG (Chip onGlass) method. The both circuits are further connected to a controlcircuit 19. Display elements 20 are sandwiched between each pixelelectrode of the active matrix thin film transistor substrate 16 and anopposing electrode 21. The thin film transistor, which is connected tothe gate wiring/electrode to which the scanning voltage that is outputfrom the gate scanning circuit 17 is applied, is operated to apply thesignal voltage supplied from the signal circuit synchronized with thescanning voltage to the pixel electrode connected to the thin filmtransistor, subjecting the display elements to so-called line sequentialdrive to operate the display device. As the display elements 20,capacitance driving elements such as liquid crystal display elements orelectrophoresis elements can be applied to the configuration of the thinfilm transistor substrate of the present invention. In the case of theIn-Plane-Switching liquid crystal display device, the opposing electrode21 is constructed within the thin film transistor as is well known, sothe configuration is different from the present figure. However,basically, the above can be applied in a same manner. Further, currentdriving display elements such as an organic electroluminescent device(OELD) can be applied, if a well known active matrix thin filmtransistor substrate for driving OELD is constructed according to thepresent invention. This display device can be applied to the flatdisplay for cellular phones, flat TVs, note PCs and the like.Furthermore, it is needless to say that the thin film transistor of thepresent invention can be applied to all semiconductor devices utilizingthin film transistors such as RFID devices typified by non-contact ICcards, other than display devices.

EXAMPLE 6

In the present example, a back-surface exposure method and deviceconfiguration of a photosensitive liquid-repellent film are describedwith reference to FIG. 15 showing the schematic configuration thereof. Asubstrate 1, on which a lower electrode 2 and an insulating film 3 arelayered in this order and then a photosensitive liquid-repellent film 4is dip-coated, is provided. In this case, the photosensitiveliquid-repellent film 4 is attached to the back-surface of the substrate1 and to the surface of the insulating film 3. A photocatalyst film 24typified by titanium oxide having a thickness of about 200 nm, which isformed on the surface of a supporting plate 23 comprised of aluminum orthe like in which heating mechanism such as a sheathed heater is built,is adhered to the above substrate 1 (FIG. 15( a)). In order to improvethe adhesion, it is effective to place a rubber sheet comprised of PDMSor the like between the supporting plate 23 and the photocatalyst film24 as a cushioning material. When irradiating the back-surface of thesubstrate 1 with the light having the wavelengths that transmit thesubstrate and the insulating film and is absorbed by the photocatalystfilm, hole carriers having a strong oxidizing power are produced on thesurface of the photocatalyst film 24. These hole carriers directlydecompose the adjacent photosensitive liquid-repellent film and thephotosensitive liquid-repellent film 4 is processed to a generally samepattern shape as the lower electrode 2. At this time, when thephotocatalyst film 24 was preliminarily heated by the heating mechanismto 100° C. or above, the pattern processing accuracy of thephotosensitive liquid-repellent film 4 was improved, and it was possibleto process it to a minimum pattern width of 3 μm. It is contemplatedthat when moisture attaches to the surface of the photosensitiveliquid-repellent film, the hole carriers will oxidatively decomposewater to produce an OH group, which will indirectly decompose thephotosensitive liquid-repellent film; and the OH group will float andmove in the space between the photocatalyst film 24 and thephotosensitive liquid-repellent film 4 to decompose and remove even thephotosensitive liquid-repellent film 4 in a shielded region. Whenadsorbed moisture is preliminarily removed from the surface of thephotosensitive film by heating, the indirect decomposition process bythe OH group does not work, but only the direct decomposition process bythe hole carriers having a short moving distance does work, improvingthe pattern processing accuracy of the photosensitive liquid-repellentfilm 4. In addition, the photocatalyst film 24 not with a irregularsurface but with a smoother surface improves the adhesion between thephotocatalyst film 24 and the photosensitive liquid-repellent film 4,improving the pattern processing accuracy and efficiency.

As described in Example 1, when titanium oxide is used as aphotocatalytic material, the exposure wavelengths are 400 nm or less,and so materials to transmit these wavelengths are used for thesubstrate 1 and the insulating film 3. When a visible-light-responsivephotocatalytic material such as nitrogen-doped titanium oxide is used,the exposure wavelengths are 600 nm or less, and so materials totransmit these wavelengths are used for the substrate 1 and theinsulating film 3. In the present method, the photocatalytic material isnot used in the insulating film, so organic materials having the aboveconditions can be used for the insulating film 3 and the semiconductorfilm 7. Further, when the photosensitive film is processed by thepresent method, the light having the wavelengths that do not directlyprocess the photosensitive liquid-repellent film can be used. Therefore,as for the materials for the electrode substrate, when for example afluorinated alkyl silane coupling agent having a photosensitivewavelength of 300 nm or less is used as the photosensitiveliquid-repellent film 4, materials that are opaque to the photosensitivewavelengths of the photosensitive liquid-repellent film can be used forat least one of the substrate and the insulating film, such as a glasssubstrate such as Corning 1737 for the substrate 1 or an organicmaterial such as PVP for the insulating film 3.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. An electrode substrate comprising a substrate, a lower electrode, aninsulating film having a liquid-repellent region and a liquid-attractingregion on a surface thereof and an upper electrode, wherein the lowerelectrode, the insulating film and the upper electrode are layered inthis order on the substrate; wherein a pattern shape of the lowerelectrode generally matches with that of the liquid-repellent region onthe surface of the insulating film; and wherein the upper electrode isformed mainly on the liquid-attracting region excluding theliquid-repellent region on the surface of the insulating film, such thatthe pattern shape of the upper electrode is a self-aligned shape inwhich the pattern shape of the lower electrode is generally reversed. 2.A thin film transistor comprising the electrode substrate according toclaim 1 and a semiconductor film, wherein, on the electrode substrate, agate electrode is formed as the lower electrode, and a source electrodeand a drain electrode are formed as the upper electrodes on therespective liquid-attracting regions isolated into two or more regionsby the liquid-repellent region formed on the surface of the insulatingfilm in a pattern shape that generally matches with the lower electrode,such that the pattern shape of the upper electrodes is a self-alignedshape in which the pattern shape of the gate electrode, i.e., the lowerelectrode, is generally reversed; and wherein the semiconductor film isformed such that it extends over and covers at least a part of each ofthe source electrode, the drain electrode and the surface of theinsulating film (gate electrode region) lying therebetween over/on saidelectrode substrate.
 3. An active matrix thin film transistor substratecomprising the electrode substrate according to claim 1 and thin filmtransistors having semiconductor films, wherein, on the electrodesubstrate, a plurality of gate wirings/electrodes is formed as the lowerelectrodes, and a plurality of signal wirings, source/drain electrodesand pixel electrodes are formed as the upper electrodes on theliquid-attracting regions isolated into a plurality of regions by theliquid-repellent regions formed on the surface of the insulating film ina pattern shape that generally matches with the lower electrodes;wherein the semiconductor films are formed such that they extend overand cover at least a part of each of the source electrodes, drainelectrodes and liquid-repellent regions (gate wiring/electrode regions)on the surface of the insulating films lying therebetween over/on theelectrode substrate; and wherein the thin film transistors are eachplaced at each intersection of the gate wiring and signal wiring.
 4. Theactive matrix thin film transistor substrate according to claim 3,wherein a plurality of gate wirings/electrodes, having a shape in whicha plurality of adjacently placed ring-shaped rectangles each having anopening are connected to each other at least at one or more locations,are adjacently placed to each other as the lower electrodes; whereinsignal wirings and source/drain electrodes are each formed on the spacebetween said rectangles in a continuous shape spreading over theconnection in a self-aligned manner with respect to said gatewirings/electrodes as the upper electrodes; and wherein the pixelelectrodes are each formed in an opening of said ring-shaped rectangle.5. The active matrix thin film transistor substrate according to claim4, wherein a width of the connection part for connecting each of aplurality of rectangles each having an opening for composing gatewirings/electrodes and a width of a space between a plurality of gatewirings/electrodes are smaller than a width of a space between aplurality of rectangles each having an opening for composing gatewirings/electrodes.
 6. A liquid crystal, electrophoresis, or organicelectroluminescent display device, which comprises the thin filmtransistor substrate according to any one of claims 3 to 5 as an activematrix switch.
 7. An RFID device, which comprises the thin filmtransistor according to claim 2 as at least a part thereof.
 8. Theelectrode substrate, thin film transistor and active matrix thin filmtransistor substrate according to any one of claims 1 to 3, whichcomprises a photosensitive liquid-repellent monolayer comprising acarbon chain in which at least a part thereof is terminated withfluorine or hydrogen as a photosensitive liquid-repellent film.
 9. Theelectrode substrate according to claim 1, wherein at least one of thesubstrate and the insulating film is formed by a material that does nottransmit a light with a photosensitive wavelength of theliquid-repellent film.
 10. The thin film transistor according to claim2, wherein at least one of the substrate and the insulating film isformed by a material that does not transmit a light with aphotosensitive wavelength of the liquid-repellent film.
 11. The activematrix thin film transistor substrate according to any one of claims 3to 5, wherein at least one of the substrate and the insulating film isformed by a material that does not transmit a light with aphotosensitive wavelength of the liquid-repellent film.